Canted rudders for ses



United States Patent [5 6] References Cited UNITED STATES PATENTS 2,263,529 11/1941 Dow 114/163 3,249,081 5/1966 Schuster 114/152 Primary Examiner-Andrew l-l. Farrell Attorneys- L. A. Miller, Q. E. Hodges and A. Sopp ABSTRACT: A canted rudder system for a rigid sidewall surface effect watercraft. A rudder rotatable about an outwardly and downwardly canted axis is located at the afterend of each rigid sidewall. Turning of the rudders in the same directional sense produces a banked turn with the inward side and its stern held in a down position. For emergency braking the rudders may be rotated oppositely.

PATENTEU DEE22 I976 SHEET 1 OF 2 INVENTORS ALLEN 6. FORD ROBERT 4, WILSON ATTORNEYS CANTED RUDDERS FOR SES The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION SUMMARY According to the invention an outwardly and downwardly canted rudder is mounted behind the stem end of each sidewall. At the stern of each sidewall a rudder postextends to the upper, forward end of the rudder at which point the post is canted outwardly to form part of the integral structure of the rudder. Suitable cockpit controls are provided so that the rudders may be rotated in the same or opposite senses. Rotating in one directional sense of one or more of the rudders into the free stream flow causes yaw and roll forces to act on the craft, the result being a banked turn in which the inward side is pulled down. Rotating both rudders in opposite directions from each other produces bow-up braking of the craft.

Accordingly, it is among the objects of the present invention to provide improved control for a CAB vehicle; improved rollheave-yaw control forv a CAB vehicle thruemployment of canted rudders; improved seaworthiness of a CAB vehicle thru employment of stem mounted outwardly canted rudders enabling inward banking diving turns and preventing escape of the vehicle-supporting air bubble.

BRIEF DESCRIPTION OF THE DRAWINGS For a bettetzunderstanding of the objects, features and advantages of the present invention, reference is made to the following detailed description and accompanying drawings, FIGS. 1-4. FIGS. .1 and 2 are respectively plan and stem-on views of a CAB vehicle showing the preferred embodiment of the rudder and control system according to the principles of the invention. FIGS. 3 and 4 are respectively plan and stem-on views of a CAB vehicle having an alternate embodiment of the rudder and control system according to the principles of the invention.

DETAILED DESCRIPTION Referring to FIGS. 1 and 2, a CAB vehicle 11 is shown having port and starboard rigid sidewalls l3 and 15 terminating at their respective vertical stern portions 17 and 19. The bottoms 21,23 of the respective sidewalls cant inwardly to provide lateral stability for the vehicle. The air cushion plenum or bubble is contained by the sidewalls'and by fore and aft seals (not shown).

A pilots control station 27 has steering control units 29 and 29a of any suitable well known design having first and second pairs of control lines 31 and 31a respectively extending to port and starboard hydraulic actuators 33. Each actuator 33 may be of conventional construction and has a lateral piston rod 35 pivotally attached to a shaft arm 37. Each shaft arm 37 rotates with a rudder post 39 extending vertically at the stem. Control unit 29 moves port and starboard rods in the same directions; unit 29a moves the rods in opposite directions.

Each rudder post 39 has suitable upper and lower fastening means securing the post to the stem. Below the lower fasten ing, the rudder post on the portside extends outwardly and downwardly beyond the lowermost portion of the sidewalls in a portside outwardly canted portion 41, there being a similar canted rudder post portion 43 for the starboard side. A port rudder 45 is integrally attached to and extends aft of canted rudder portion 41, and a starboard rudder 47 is similarly attached to rudder post portion 43 on the starboard side. Canted rudder post portions 41 and 43 may form the leading edges of the respective rudders, or be embedded herein.

Upon clockwise rotation of the port and starboard rudder posts by enforcing appropriate hydraulic pressures in lines 31, actuators 33 acting on arms 35,37, the starboard rudder assumes a positive attach angle to the free stream and the portside rudder, a negative attack angle. Therefore, the starboard side of the craft lifts up, and the portside pulls down. Said rotation of the rudders also produces a turning moment about the center of lift of the craft, causing a turn to port. Of course, a starboard turn is accomplished by counterclockwise rotation of the rudder posts. Because the rudders are located at the aft end of the craft, the craft is both heeled or banked into the turn as well as rotated, the attack angle of the inward rudder pulling the inward side of the stern downward. Consequently, forces are generated positively preventing roll-heave-yaw instability which would otherwise cause severe broaching during a turn.

If desired, the rudders mounted as described may be employed as brakes, say, in an emergency, to prevent yawing of the craft in straight travel. Rotating the port and starboard rudders oppositely via control unit29a, lines 31a, produces drag at the stem tending to pull the stern down and preventing dangerous pitching and yaw. For producing approximately equal amounts of lift and turning at each rudder, they may be canted at an angle of about from the sidewall, or 45 from horizontal. Referring now to FIGS. 3 and 4 the CAB vehicle is shown as substantially the same as in FIGS. 1 and 2 but with an alternate rudder and control system. The pilots control station 27 contains steering control units 50 and 50a of any suitable well known design having first and second pairs of control lines 51 and 510, respectively, extending to port and starboard hydraulic actuators 53. Actuators 53 rotatably drive shafts 55 operatively connected thereto. With respect to a plane parallel to the stern, control unit 50 rotates port and starboard shafts in opposite directions while control unit 50a rotates port and starboard shaft in the samedirection. 0n the port side, shaft 55 is operatively coupled to port rudder bevel gear 63 through right angle drive 57, rudder gear shaft 50 and complementary gear 61. Attached to port bevel gear 63 at its axis and rotating with it is port rudder shaft 65 extending outwardly and downwardly beyond the lower most portion of the sidewall in a portside outwardly directioncA port rudder 67 is attached to port rudder shaft 65 and extends aft of the port rudder shaft. The starboard rudder 73 is similarly attached to starboard rudder shaft 71 and starboard rudder bevel gear 69. Each rudder shaft has suitable rotatably fastening means securing it in the stern. For producing. equal moments of tuming and banking, at each rudder, each are mounted at the same angular displacement from the horizontal and present a mirror image about a vertical plane through the center line of bevel gears 63 to rotate port rudder shaft 65 and the port,

rudder to a negative attack angle to the free stream flow, starboard complementary gear 61 engaged with starboard bevel gear 69 and rotating clockwise causes support bevel gear 69 to rotate starboard rudder shaft 7 I and the starboard rudder to a positive attack angle to the free stream flow. Therefore the port side of the craft is pulled down and the starboard side lifts up. Said rotation of the rudders also produces a taming moment about the center of lift of the craft causing theturn to port. A starboard turn is accomplished by rotating the shafts in opposite directions to the rotation required for a port turn. If

desired, the rudders as described may be applied as brakes by rotating actuators 53 in the same direction causing the port starboard rudders to present the'same angle of attack to the free stream and producing drag at the stern.

The actuation of the rudders may not be hydraulic but may be any other suitable well known means. The advantage of the arrangement shown in FIGS-l and 2 is that the entire rudder is disposed below and behind the sidewalls thereby increasing rudder efficiency for both turning and lifting, as well as insuring rudder immersion.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described.

We claim:

1. A canted rudder system for a surface effect vehicle having port and starboard rigid sidewalls enclosing a vehicle-supporting air bubble comprising:

rudder post means attached to the stem end of each sidewall;

a rudder rotatable with eachsaid rudder'post means, about a canted ai'ris, a portion of said canted axis extending outwardly and downwardly from the sidewallyand means for actuating said rudder posts to move said rudders to positions in the free stream flow to effectuate banked turning and bow-up braking of the crafi.

2. A canted rudder system for a surface effect vehicle having port and starboard rigid sidewalls enclosing a vehicle-sup porting air bubble comprising: a rudder post means attached to the stern end of each sidewall; said rudder post means including:

an essentially upstanding post rotatably attached to the stern;

an outwardly and downwardly canted post portion integral with said upstanding post for rotation therewith; and

said canted post portion being rigidly attached to therudder at least near the leading edge of the rudder.

3. Apparatus according to claim 2 wherein the surfaces of the canted rudders are essentially entirely below the bottom most surfaces of the sidewalls.

4. Apparatus according to claim 1 wherein the rudders are canted at an angle of about 45 below horizontal.

5. Apparatus according to claim 1 wherein the surfaces of said rudders are essentially entirely below the bottom most surfaces of the sidewalls.

'6. Apparatus according to claim 2 wherein the rudders are canted at an angle of about 45 below horizontal. 

